Joint diseases such as rheumatoid arthritis are among the autoimmune diseases which affect a steadily growing segment of society. They involve painful inflammation and can in the worst case even lead to the destruction of the joints. Researchers led by Prof. Dr. Falk Nimmerjahn of the Department of Genetics at FAU have worked together with the research groups of Prof. Dr. Georg Schett at FAU’s University Hospital and Prof. Dr. Jan Tuckermann from the University of Ulm to show that in patients with rheumatoid arthritis, own defence cells directly influence the cells responsible for bone resorption. The results of their research have now been published in the latest issue of the renowned journal PNAS.

Defence cells, also known as antibodies, are proteins that normally recognise and destroy pathogens in the body. However, in patients with autoimmune diseases, the immune system gets out of control and forms so-called autoantibodies that attack the body’s own tissue. In the case of rheumatoid arthritis, this leads to a loss of cartilage and bone substance. The FAU researchers have proven that the autoantibodies directly influence the cells that are responsible for bone resorption, the osteoclasts.

A healthy person’s skeletal system is undergoing a constant process of renewal, with bone resorption and formation balancing each other out. The Erlangen researchers’ work has now shown that the autoantibodies upset this balance in the affected joint in favour of bone resorption. This explains the pathological changes all the way to the destruction of the joint. When the scientists blocked the interaction of the autoantibodies with the bone-eating osteoclasts in an experiment, they were able to stop the destruction of the joint almost completely.

‘These results present an important basis for our general understanding of rheumatoid arthritis as well as for the development of new treatment approaches,’ says Professor Nimmerjahn. Currently only about 30 to 40 percent of patients respond well to common forms of treatment, which is why researchers are putting a strong focus on this disease. In co-operation with experimental and clinical research groups of the DFG Priority Programme Osteoimmunology, which is co-ordinated at FAU, researchers will spend the coming years translating these insights into new diagnostic and therapeutic procedures, thus allowing patients to benefit from them.